1. Field of the Invention
The present invention relates to an image display panel, a method for driving an image display apparatus employing the image display panel, an image display apparatus assembly including the image display apparatus and a method for driving the image display apparatus assembly.
2. Description of the Related Art
In recent years, an image display apparatus such as a color liquid-crystal display apparatus raises a problem of increased power consumption as a consequence of a raised performance. In particular, a higher resolution, widened color reproduction range and higher luminance of a color liquid-crystal display apparatus undesirably raise a problem of increased power consumption of a backlight employed in the apparatus.
In order to solve this problem, there has been provided a technology for raising the luminance. In accordance with this technology, each display pixel is configured to include four sub-pixels, i.e., typically, a white-color display sub-pixel for displaying the white color in addition to the three elementary-color display sub-pixels, that is, a red-color display sub-pixel for displaying the elementary red color, a green-color display sub-pixel for displaying the elementary green color and a blue-color display sub-pixel for displaying the elementary blue color. That is to say, the white-color display sub-pixel increases the luminance.
The 4-sub-pixel configuration according to the provided technology is capable of providing a high luminance at the same power consumption as the existing technology. Thus, if the luminance of the provided technology is set at the same level as the existing technology, the power consumption of the backlight can be decreased and the quality of the displayed image can be improved.
As a typical example of the existing image display apparatus, a color image display apparatus is disclosed in Japanese Patent No. 3167026. The color image display apparatus employs:
means for generating three color signals of three different hues from a sub-pixel input signal in accordance with a 3-elementary-color addition method; and
means for generating a supplementary signal obtained as a result of a color addition operation carried out on the color signals of the three different hues at the same addition ratio and for supplying a total of four different display signals, composed of the supplementary signal and three different color signals obtained as a result of subtracting the supplementary signal from the color signals of the three hues, to a display section.
It is to be noted that the color signals of the three different hues are used to drive respectively the red-color display sub-pixel for displaying the elementary red color, the green-color display sub-pixel for displaying the elementary green color and the blue-color display sub-pixel for displaying the elementary blue color whereas the supplementary signal is used to drive the white-color display sub-pixel for displaying the white color.
As another typical example of the existing image display apparatus, a liquid-crystal display apparatus capable of displaying color images is disclosed in Japanese Patent No. 3805150. The color liquid-crystal display apparatus employs a liquid-crystal display panel having main pixel units which each include a red-color output sub-pixel, a green-color output sub-pixel, a blue-color output sub-pixel and a luminance sub-pixel. The color liquid-crystal display apparatus further has processing means for finding a digital value W for driving the luminance sub-pixel, a digital value Ro for driving the red-color output sub-pixel, a digital value Go for driving the green-color output sub-pixel and a digital value Bo for driving the blue-color output sub-pixel by making use of a digital value Ri of a red-color input sub-pixel, a digital value Gi of a green-color input sub-pixel and a digital value Bi of a blue-color input sub-pixel. The digital value Ri of the red-color input sub-pixel, the digital value Gi of the green-color input sub-pixel and the digital value Bi of the blue-color input sub-pixel are digital values obtained from an input image signal. In the color liquid-crystal display apparatus, the processing means finds the digital value W, the digital value Ro, the digital value Go and the digital value Bo which satisfy the following conditions:
Firstly, the digital value W, the digital value Ro, the digital value Go and the digital value Bo shall satisfy the following equation:Ri:Gi:Bi=(Ro+W):(Go+W):(Bo+W)
Secondly, due to the addition of the luminance sub-pixel, the digital value W, the digital value Ro, the digital value Go and the digital value Bo shall result in a luminance stronger than the luminance of light emitted by a configuration composed of only the red-color output sub-pixel, the green-color output sub-pixel and the blue-color output sub-pixel.
In addition, PCT/KR 2004/000659 also discloses a liquid-crystal display apparatus which employs first pixels each including a red-color display sub-pixel, a green-color display sub-pixel and a blue-color display sub-pixel as well as second pixels each including a red-color display sub-pixel, a green-color display sub-pixel and a white-color display sub-pixel. The first pixels and the second pixels are laid out alternately in a first direction as well as in a second direction. As an alternative, in the first direction, the first pixels and the second pixels are laid out alternately but, in the second direction, on the other hand, the first pixels are laid out adjacently and, thus, the second pixels are also laid out adjacently as well.